Expandable Mesh Platform for Large Area Ablation

ABSTRACT

An ablation device and a method of ablating a tissue are provided. The ablation device includes a first elongate shaft having a proximal portion, a distal portion and a lumen extending at least partially therethrough and a second elongate shaft having a proximal portion, a distal portion and a lumen extending at least partially therethrough. The first elongate shaft is coaxially positioned and longitudinally movable relative to the second elongate shaft. The ablation device further includes a mesh member including a proximal portion and a distal portion. The proximal portion of the mesh member is operably connected to the distal portion of the second elongate shaft and the distal potion the mesh member is operably connected to an inner surface of the distal portion of the first elongate shaft. The mesh member includes a conductive portion configured to contact a surface for ablation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.14/184,438 filed Feb. 19, 2014, which claims the benefit under 35 U.S.C.§ 119 of U.S. Patent Application No. 61/767,067 filed Feb. 20, 2013;which are incorporated by reference in their entirety.

BACKGROUND

Endoscopic treatment of gastrointestinal disorders often requires theneed to coagulate tissue for the purpose of hemostasis and/or marking ofthe tissue. Areas of diseased tissue within the gastrointestinal tractmay also be treated using an ablation device. Some ablation devices maybe delivered endoscopically.

Radiofrequency ablation (RFA) is one method that can be used to deliverenergy for treating or marking the tissue. A bipolar probe is a commonlyused RFA device, for example, the Quicksliver Bipolar Probe (CookMedical, Inc., Bloomington, Ind.) Typical RFA probes are 7 to 10 Fr withelectrodes mounted on a ceramic tip on the distal end of the device. Onedrawback of these probes is that the size of the ablation zone isdependent on the size of the catheter and cannot be altered by the user.In addition, the user must use caution when applying energy when usingthis type of bipolar probe. Since all the force is distributed across asmall (7 or 10 Fr) surface area, an area of high pressure is createdincreasing the risk of perforation of the tissue at the treatment site.

What is needed in the art is an ablation treatment device that is simpleto use, reduces the risk of tissue perforation and is expandable andcollapsible to treat larger tissue areas.

BRIEF SUMMARY

Accordingly, it is an object of the present invention to provide adevice and a method having features that resolve or improve on one ormore of the above-described drawbacks.

An ablation device is provided. In some embodiments, the ablation deviceincludes a first elongate shaft having a proximal portion, a distalportion and a lumen extending at least partially therethrough and asecond elongate shaft having a proximal portion, a distal portion and alumen extending at least partially therethrough. The first elongateshaft is coaxially positioned and longitudinally movable relative to thesecond elongate shaft. The ablation device further includes a meshmember including a proximal portion and a distal portion. The proximalportion of the mesh member is operably connected to the distal portionof the second elongate shaft and the distal potion the mesh member isoperably connected to an inner surface of the distal portion of thefirst elongate shaft. The mesh member includes a conductive portionconfigured to contact a surface for ablation.

In some embodiments the ablation device includes a mesh member includinga proximal portion and a distal portion, the mesh member having a firstdiameter and a second diameter greater than the first diameter such thatthe mesh member is movable to the second diameter by moving the proximalportion relative to the distal portion. The mesh member includes aplastic material and a conductive portion, the conductive portioncomprising an ink covering at least a portion of the plastic materialand the conductive portion is positionable to contact a surface forablation.

In another embodiment, a method of ablating a tissue is provided. Themethod includes inserting a distal portion of an ablation device into alumen of a patient. The ablation device includes a first elongate shafthaving a proximal portion, a distal portion and a lumen extending atleast partially therethrough and a second elongate shaft having aproximal portion, a distal portion and a lumen extending at leastpartially therethrough. The first elongate shaft is coaxially positionedand longitudinally movable relative to the second elongate shaft. Theablation device further includes a mesh member including a proximalportion and a distal portion. The proximal portion of the mesh member isoperably connected to the distal portion of the second elongate shaftand the distal potion the mesh member is operably connected to an innersurface of the distal portion of the first elongate shaft. The meshmember includes a conductive portion configured to contact a surface forablation. The method further includes positioning a portion of themechanically expandable ablation member at a treatment site, moving thefirst elongate shaft relative to the second elongate shaft to move theablation device to an expanded configuration having the second diameter,pressing an end face of the mesh member against the surface and applyingenergy to the tissue from an energy source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial view of a distal portion of an ablation device in anextended configuration accordance with an embodiment of the presentinvention;

FIG. 2 is partial view of the ablation device shown in FIG. 1 with amesh member removed;

FIG. 3 is a partial view of the ablation device shown in FIG. 1 in anexpanded configuration;

FIG. 4 is a partial view of the ablation device shown in FIG. 3 with themesh member removed;

FIG. 5 is a partial view of an embodiment the distal portion of theablation device;

FIG. 6 is a partial side view of an embodiment the distal portion of theablation device;

FIG. 7 is a partial side view of an embodiment the distal portion of theablation device;

FIG. 8 is an end view of an end face of an embodiment of the ablationdevice in an expanded configuration;

FIG. 9 is an end view of an end face of an embodiment of the ablationdevice in an extended configuration;

FIGS. 10-13 show a partial view of a distal portion of an embodiment ofthe ablation device moving from an extended configuration to an expandedconfiguration to a retracted configuration;

FIG. 14 is a partial view of a proximal portion of an embodiment of theablation device;

FIG. 15 is a partial sectional view of a distal portion an embodiment ofthe ablation device;

FIG. 16 is an end view of an end face of an embodiment of the ablationdevice; and

FIGS. 17A-17C illustrate operation of the ablation device.

DETAILED DESCRIPTION

The invention is described with reference to the drawings in which likeelements are referred to by like numerals. The relationship andfunctioning of the various elements of this invention are betterunderstood by the following detailed description. However, theembodiments of this invention are not limited to the embodimentsillustrated in the drawings. It should be understood that the drawingsare not to scale, and in certain instances details have been omittedwhich are not necessary for an understanding of the present invention,such as conventional fabrication and assembly.

As used in the specification, the terms proximal and distal should beunderstood as being in the terms of a physician delivering the ablationdevice to a patient. Hence the term “distal” means the portion of theablation device that is farthest from the physician and the term“proximal” means the portion of the ablation device that is nearest tothe physician.

FIGS. 1 and 2 illustrate an embodiment of an ablation device 10 inaccordance with the present invention. The ablation device 10 includesan outer catheter 12, an inner catheter 14, one or more drive cables 16and a mesh member 20. The inner catheter 14 and the drive cable 16 areshown in FIG. 2 without the mesh member 20 so that the inner catheter 14and the drive cable 16 can be more readily viewed. The inner catheter 14may be coaxially positioned within the outer catheter 12 and slidablypositionable relative to the outer catheter 12. The outer catheter 12includes a proximal end portion 22, a distal end portion 24 and a lumen26 extending at least partially therethrough. The inner catheter 14includes a proximal end portion 32, a distal end portion 34 and a lumen36 extending at least partially therethrough. The drive cable 16 isshown extending through the lumen 36 of the inner catheter 14 in FIG. 2.In some embodiments, the drive cable 16 may be positioned external tothe inner catheter 14. The drive cable 16 is movable relative to theouter catheter 12 and in some embodiments the drive cable 16 is movabletogether with the inner catheter 14.

The mesh member 20 is operably connectable to the inner catheter 14, theouter catheter 12 and the drive cable 16. As the inner catheter 14 andthe outer catheter 12 are moved relative to each other, the shape of themesh member 20 changes. In some embodiments, a distal end portion 38 ofthe mesh member 20 may be extended over a distal end 39 of the innercatheter 14, inverted into the lumen 36 of the inner catheter 14 andoperably connected to an inner surface 41 of the distal end portion 34of the inner catheter 14. The drive cable 16 may also be operablyconnected to the mesh member 20 to move the mesh member 20 and the innercatheter 14 relative to the outer catheter 12. The drive cable 16 mayalso act as the active wire to transmit current from an electrosurgicalunit (ESU) to the mesh member 20 and to the tissue (described in moredetail below). A proximal end portion 40 of the mesh member 20 may beoperably connected to the distal end portion 26 of the outer catheter12.

FIG. 1 illustrates an extended configuration 44 of the device 10 wherethe distal end portion 36 of the inner catheter 14 is extended distal tothe distal end portion 26 of the outer catheter 12 and the mesh member20 is fully extended so that the mesh member 20 has an outer diameter d₁at a distal portion 46 of an outer surface 48 of the mesh member 20 thatis about the same as an outer diameter d₂ of the outer catheter 12. Themesh member 20 expands, extends and retracts by longitudinal movement ofthe inner catheter 14 relative to the outer catheter 12. The ablationdevice 10 may be delivered to the treatment site with the device 10 inthe extended configuration 44. An outer sheath 70 may be positioned overthe ablation device 10 for delivery to a treatment site. (See FIG. 15showing an outer sheath.)

FIGS. 3 and 4 illustrate the ablation device 10 in an expandedconfiguration 54. Similar to FIG. 2 above, FIG. 4 illustrates the outercatheter 12, the inner catheter 14 and the drive cable 16 without themesh member 20 so that the inner catheter 14 and the drive cable 16 canbe more readily viewed. The inner catheter 14 is shown in FIG. 4proximally withdrawn relative to the position of the inner catheter 14shown in FIG. 2. The distal end portion 34 of the inner catheter 14 isstill distal to but closer to the distal end portion 24 of the outercatheter 12. As shown in FIG. 3, with the inner catheter 14 proximallywithdrawn relative to the outer catheter 12 and still having the distalend portion 34 distal to the distal end portion 24, the mesh member 20is radially expanded relative to the extended configuration 44 and hasan outer diameter d₃ at the distal portion 46 of the outer surface 48 ofthe mesh member 20. The outer diameter d₃ is greater than the diametersd₁ and d₂. As shown in FIG. 3, the inner catheter 14 can be withdrawn tothe point where an end face 56 of the mesh member 20 forms a generallyflattened surface that can be advanced into contact with the tissue atthe treatment site.

FIGS. 5 and 6 illustrate the ablation device 10 in the expandedconfiguration 54 with the end face 56 of the mesh member 20 flattenedagainst a surface S for treatment. As shown in FIG. 5, the ablationdevice 10 may be used with the inner and outer catheters 14, 12generally perpendicular to the treatment surface S. As shown in FIG. 5,the end face 56 is generally flattened against the treatment surface Sand can form an ablation disc in the tissue since the end face 56 of themesh member 20 can directly contact the tissue across the entire surfaceof the end face 56. The end face 56 can be pressed against the tissueand generally flattened without application of undue force to flattenthe end face 56. The risk of perforation of the tissue is also reduceddue to the decreased pressure and to the spreading of the energy acrossthe end face 56.

FIG. 6 illustrates the ablation device 10 in the expanded configuration54 with the end face 56 flattened against a surface S for treatment. Insome embodiments, the mesh member 20 is made of a flexible material thatallows the end face 56 of the mesh member 20 to contact the surface Sfor treatment with the inner catheter 14 and the outer catheter 12positioned at an oblique angle 60 relative to the surface S. By way ofnon-limiting example, the mesh member 20 may be formed of a plasticmaterial coated with a conductive material (described in more detailbelow) that is flexible enough to bend and flatten the end face 56against the surface S by moving the mesh member 20. In some embodiments,the ablation device 10 may include a hinge 64 as shown in FIG. 7 tofacilitate positioning of the end face 56 against the surface S. Asshown in FIG. 7, the outer catheter 12 to be extended generallyperpendicular to the surface S for treatment and the hinge 64 allows themesh material 20 to bend at the oblique angle 60 so that the end face 56of the mesh material 20 is positioned flat against the surface S fortreatment of the tissue. In some embodiments, the hinge 64 may be on theinner catheter 14 and the outer catheter 12. The hinge 64 may be usedwith mesh materials that are formed from stiffer materials, for examplesome metal meshes may be too rigid to deform easily against the surfaceS and would require too much pressure against the surface S to flattenthe end face 56. The hinge 64 may be any kind of a hinge that allows theablation device 10 to be delivered to the site, bent at an angle andthen returned to the generally straight configuration for withdrawalfrom the patients. The bending at an angle and return of the ablationdevice 10 to the straightened position may be by mechanical means suchas a drive cable or by contact with a portion of the body lumen.

An end view of the end face 56 of the mesh member 20 in the expandedconfiguration 54 is shown in FIG. 8. The entire end face 56 may beenergized for treatment of tissue or portions of the end face 56 may beenergized as describe in more detail below. The end face 56 is shown ashaving a generally circular face, however other shapes may also be used.By way of non-limiting example, other shapes for the end face 56 may beformed by changing the weave pattern of the mesh member 20, for exampleforming an oval or a ring. The weave pattern may be varied to alsochange the overall size of the end face 56 to create a different sizetreatment area. In some embodiments, the density of the weave pattern orthe thickness of the woven portions may also be varied to change theenergy delivered to the treatment area and the flexibility of the meshmaterial 20. The size of the inner catheter 12 and the attachment of themesh member 20 may also contribute to the size, density and energydelivery of the end face 56. As shown in FIG. 8, the mesh member 20 maybe folded over the distal end portion 34 of the inner catheter 14 andextend into the lumen 36 and be connected to the inside of the catheter14. The mesh member 20 may extend across a portion of the lumen 36 sothat the end face 56 may be used to ablate an entire disc of tissue. Insome embodiments, the lumen 36 may be at least partially free from themesh member 20 if a ring is desired for the treatment area.

FIG. 9 illustrates an end view of the end face 56 of the mesh member 20in the extended configuration 44. The diameter d₁ and thus the surfacearea of the end face 56 in the extended configuration 44 is smaller thanthe diameter d₃ of the end face 56 in the expanded configuration 54. Theablation device 10 may be used in the extended configuration 44 so thatthe end face 56 is energized to treat a smaller tissue area. In someembodiments, the mesh member 20 may be configured so that the end face56 may be energized or a portion of the outer surface 48 of the meshmember 20 may be energized with the ablation device 10 in the extendedconfiguration 44 (See also FIG. 1.) The mesh may be formed from wiresuch as nickel titanium alloys, for example, nitinol, stainless steel,cobalt alloys and titanium alloys. In some embodiments, the mesh may beformed from a polymeric material such as a polyolefin, a fluoropolymer,a polyester, for example, polypropylene, polytetrafluoroethylene,polyvinylidene fluoride, polyethylene terephthalate (PET), andcombinations thereof. Other materials known to one skilled in the artmay also be used to form the mesh member 20.

FIGS. 10 to 13 illustrate movement of the mesh member 20 of the ablationdevice 10. As shown in FIGS. 10 to 13, the mesh member 20 is moved bymoving the inner catheter 14 relative to outer catheter 12 so thatdistal end portion 34 of the inner catheter 14 is moved closer to thedistal end portion 24 of the outer catheter 12. The drive cable 16 mayalso be used to move the inner catheter 14 relative to the outercatheter 12. The ablation device 10 is in the extended configuration 44shown in FIG. 10 with the inner catheter 14 extended to its distalmostposition relative to the outer catheter 12 so that the mesh member 20 isfully distally extended. FIGS. 11 and 12 show the inner catheter 14being proximally withdrawn relative to the outer catheter 12 and themesh member 20 expanding to the expanded configuration 54 and thediameter of the end face 56 increasing relative to the diameter of theend face 56 shown in FIG. 10. The drive cable 16 remains connected tothe mesh member 20 in all the configurations so that the ablation device10 may be energized in any of the positions shown in FIGS. 10-12. InFIGS. 10-12, the distal end portion 34 of the inner catheter 14 isdistal to the distal end portion 24 of the outer catheter 12.

FIG. 13 illustrates the mesh member 20 in a retracted configuration 68where the inner catheter 14 is positioned within the outer catheter 12so that the distal end portion 24 of the inner catheter 14 is positionedproximal to a distal end 25 of the outer catheter. The mesh member 20extends over a distal end 29 of the outer catheter 12. The distal endportion 38 of the mesh member 20 is withdrawn into the lumen 26 of theinner catheter 14 and the proximal end portion 40 of the mesh member 20remains connected to an outer surface 27 of outer catheter 12. Theablation device 10 may be moved to the retracted configuration 68 byproximally withdrawing the drive cable 16 and/or the inner catheter 14relative to the outer catheter 12. The retracted configuration 68 may beused to deliver the ablation device 10 to the treatment site. Theablation device 10 may also be moved to the retracted configuration 68from the extended or expanded configurations 44, 54 to facilitateremoval of tissue that may be adhered or caught in the mesh member 20after the tissue has been ablated. The ablation device 10 may bereturned to the extended or expanded configuration 44, 54 by moving theinner catheter 14 distally relative to the outer catheter 12 ifadditional treatments are desired. The ablation device 10 may be“cleaned” by proximal withdrawal of the inner catheter 14 relative tothe outer catheter 12 and repositioned by distally moving the innercatheter 14 relative to the outer catheter 12 as many times as neededfor a treatment procedure.

A control handle 70 is provided at a proximal portion 72 of the ablationdevice 10. An exemplary control handle 70 is shown in FIG. 14 and oneskilled in the art will recognize that other types of handles suitablefor moving the inner catheter 14 relative to the outer catheter 12 mayalso be used. By way of non-limiting example, the handle 70 includes afirst portion 73 and a second portion 75 that move relative to eachother. As shown in FIG. 14, the first portion 73 is operably connectedto the inner catheter 14. The second portion 75 is operably connected tothe outer catheter 12. The first portion 73 may be moved proximallyand/or the second portion 75 may be moved distally to move the innercatheter 14 relative to the outer catheter 12 to move the mesh member20.

The handle 70 may include a lock 76 shown in FIG. 14 to releasably lockthe first portion 73 in position relative to the second portion 75 andthus lock the mesh member 20 in position. The lock 76 may releasablylock the first and second portions 73, 75 of the handle 70 together atany proximal/distal positioning of the inner and outer catheters 14, 12so that the mesh member 20 may be locked at any size and any positionthat is suitable for the treatment site. FIG. 7 also illustrates anenergy source 84. As shown in FIG. 14, the handle 70 may include aconnector 86 for operably connecting one or more of the drive cables 16to the energy source 84 to operably connect the energy source 84 to themesh member 20. A separate wire may also be used to connect to theenergy source 84 so that the mesh member is operably connected to theenergy source 84 to supply energy to the mesh member 20 for ablation ofthe tissue. In some embodiments, the energy source 84 may be a radiofrequency source. However, other types of energy sources 84 may also beused to provide energy to the mesh member 20. By way of non-limitingexample, additional possible energy sources may include microwave,ultraviolet, cryogenic and laser energies.

In some embodiments, the ablation device 10 may include an outer sheath70 that is positionable over the outer catheter 12 and the mesh member20 when the ablation device is in the retracted configuration 68 asshown in FIG. 15 or in the extended configuration 54 (not shown). Theouter sheath 70 may be included to facilitate delivery of the ablationdevice 10 to a treatment site and to withdraw the ablation device 10after treatment.

In some embodiments, the ablation device 10 may be provided as amonopolar device or a bipolar device where the mesh member 20 includes aconductive portion 72. The mesh member 20 itself, when formed from anelectrically conductive material may be the conductive portion 72 orportions of the mesh member 20 may be conductive portions 72 withnon-conductive portions 73 being coated with an insulating material. Forexample, in a bipolar ablation device 10, an insulating material is usedbetween the active and return portions. The insulating material can alsobe used to form patterns for ablation, where conductive portions 72 ofthe mesh member 20 may be activated and non-conductive portions 73 ofthe mesh member 20 remain inactive. See for example, FIG. 16illustrating an embodiment of the ablation device 10 showing the endface 56 of the mesh member 20 having conductive portions 72 separated bynon-conductive portions 73. The non-conductive portions 73 may beprovided between conductive portions 72 of the mesh member 20 and thespace between the conductive portions 72 may be optimized to control thedepth of ablation of the target tissue. Spacing distances between theconductive portions 72 may be optimized depending on such factors as thetype of target tissue, the depth of the lesion, the type of energy andthe length of application of the energy to the tissue.

In some embodiments, the conductive portions 72 of the mesh member 20may comprise conductive ink that is applied to the exterior of the meshmember 20. The conductive ink may be applied in any pattern and spacingto be used for tissue treatment. In some embodiments, the conductive inkmay be a silver-based ink. An exemplary silver-based ink may be obtainedfrom Conductive Compounds (product number AG-510, Hudson, N.H.).However, other types of conductive ink may also be used, such asplatinum-based, gold-based and copper-based inks. The inks may beepoxy-based inks or non-epoxy inks, such as urethane inks. In someembodiments, the active portions of the mesh member 20 may compriseconductive polymers. The conductive ink may be applied to the meshmember 20 with a variety of printing processes, such as pad printing,ink jet printing, spraying, marker striping, painting or other likeprocesses. In some embodiments, the conductive ink may be applied to themesh member with by spraying, dipping, painting or an electrostaticcoating process.

The non-conductive portion 73 of the mesh member 20 may be an insulatingportion to separate conductive portions 72 of the mesh member 20. Insome embodiments, a coating may be applied to the mesh member 20 to formthe non-conductive portions 73 in a quantity that is sufficient toinsulate the conductive portions 72 from each other or to coat portionsof the mesh member 20 when the mesh member 20 itself is formed of aconductive material. In some embodiments, the insulating coating may bemade from parylene-N (poly-p-xylylene). Other xylylene polymers, andparticularly parylene polymers, may also be used as a coating within thescope of the present invention, including, for example,2-chloro-p-xylylene (Parylene C), 2,4-dichloro-p-xylylene (Parylene D),poly(tetraflouro-p-xylylene), poly(carboxyl-p-xylylene-co-p-xylylene),fluorinated parylene, or parylene HT® (a copolymer of per-fluorinatedparylene and non-fluorinated parylene), alone or in any combination.Preferred coatings will include the following properties: lowcoefficient of friction (preferably below about 0.5, more preferablybelow about 0.4, and most preferably below about 0.35); very lowpermeability to moisture and gases; fungal and bacterial resistance;high tensile and yield strength; high conformality (ready application inuniform thickness on all surfaces, including irregular surfaces, withoutleaving voids); radiation resistance (no adverse reaction underfluoroscopy); bio-compatible/bio-inert; acid and base resistant (littleor no damage by acidic or caustic fluids); ability to be applied bychemical vapor deposition bonding/integrating to wire surface (bondingis intended to contrast to, for example, fluoroethylenes that formsurface films that are able to be peeled off an underlying wire); andhigh dielectric strength.

Operation of the ablation device 10 will be explained with reference toFIGS. 17A-17C. FIG. 18A illustrates a patient's esophagus 90, loweresophageal sphincter (LES) 91 and stomach 92. Areas of diseased tissue94 within the esophagus 90 are also shown. FIG. 17B illustrates the meshmember 20 of the ablation device 10 in the retracted configuration 68being inserted into the patient's esophagus 80 for delivery to theproper position. The inner catheter 14 is positioned within the outercatheter 12 for advancement to the tissue. In some situations, theablation device 10 may be delivered using an endoscope 98 that is shownin FIG. 17C to facilitate placement of the mesh member 20 in the properposition to ablate the diseased tissue 94. The endoscope 98 may includea viewing port 99 for visualizing the diseased tissue 94 and positioningthe ablation device 10. The ablation device 10 may be delivered throughthe working channel or optionally back-loaded into the working channelof the endoscope before insertion of the endoscope 98 into the patient.As shown in FIG. 17C, the mesh member 20 of the ablation device ablationdevice 10 is delivered through the endoscope 98 and positioned so thatthe mesh member 20 is adjacent to the diseased tissue 94 in the expandedconfiguration 54. The mesh member 20 may be positioned so that the endface 56 of the mesh member 20 directly contacts the diseased tissue 94or an electroconductive fluid may be provided between the end face 56and the diseased tissue 94. The power source 84 is activated for asufficient time to ablate the diseased tissue 94. The mesh member 20 maythen be proximally withdrawn to the retracted configuration 68 byproximally moving the inner catheter 14 relative to the outer catheter12. The mesh member 20 may be repositioned at a new tissue site orremoved once the ablation of the diseased tissue is completed. While theprocedure has been described with reference to the ablation of diseasedtissue in the esophagus using the ablation device 10, the location ofthe treatment is not limited to the esophagus. By way of non-limitingexample, portions of the stomach, the gastrointestinal tract, the lungsor the vascular system may also be treated using the ablation device 10.For example, the device 10 may be used for treating bleeding varices inthe esophagus or for treatment of prostatic diseases, such as benignprostatic hyperplasia.

The above Figures and disclosure are intended to be illustrative and notexhaustive. This description will suggest many variations andalternatives to one of ordinary skill in the art. All such variationsand alternatives are intended to be encompassed within the scope of theattached claims. Those familiar with the art may recognize otherequivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the attached claims.

1. A method of ablating a tissue, the method comprising: inserting adistal portion of an ablation device into a lumen of a patient, theablation device comprising: a first elongate shaft having a proximalportion, a distal portion and a lumen extending at least partiallytherethrough; a elongate shaft having a proximal portion, a distalportion and a lumen extending at least partially therethrough, the firstelongate shaft coaxially positioned and movable relative to the secondelongate shaft; and a mesh member comprising a proximal portion and adistal portion, the proximal portion of the mesh member operablyconnected to the distal portion of the second elongate shaft and thedistal potion the mesh member operably connected to an inner surface ofthe distal portion of the first elongate shaft, the mesh member having afirst diameter and a second diameter greater than the first diameter andthe mesh member comprising a conductive portion configured to contact asurface for ablation; positioning at least a portion of the mesh memberat a treatment site; moving the first elongate shaft relative to thesecond elongate shaft to move the ablation device to an expandedconfiguration having the second diameter; pressing an end face of themesh member against the surface; and applying energy to the tissue froman energy source.
 2. The method according to claim 1, comprisinglongitudinally moving the first elongate shaft relative to the secondelongate shaft to move the ablation device to an extended configurationhaving substantially the first diameter wherein the end face isconfigured to be pressed against the surface.
 3. The method according toclaim 1, comprising longitudinally moving the first elongate shaftrelative to the second elongate shaft to move the ablation device toretracted configuration where the distal portion of the mesh member ispositioned within the lumen of the second elongate shaft and theproximal portion of the mesh member remains operably connected to theouter surface of the distal end of the second elongate shaft.
 4. Themethod according to claim 1, comprising moving the ablation device to asecond treatment site in the retracted configuration and expanding themesh member at the second site by longitudinally moving the firstelongate shaft relative to the second elongate shaft.
 5. The methodaccording to claim 1, comprising delivering the ablation device to thetreatment site using an endoscope.